Optical fibers transmit signals in the form of light. A typical optical fiber is formed of glass, and includes a central core surrounded by cladding. The core is doped so as to have a different index of refraction than the cladding. Accordingly, light travels within the core.
A waveguide may be used to transmit light from one optical fiber to another optical fiber; from a light source, such as a laser diode on a semiconductor chip, to an optical fiber; or from an optical fiber to a light sensitive circuit on a semiconductor chip. The core of the optical fiber must be precisely aligned with the waveguide in order to prevent transmission loss. A typical alignment specification is within one micron.
Practitioners have attempted to develop devices and methods that facilitate the alignment of optical fibers and waveguides. In this regard, the reader is referred to U.S. Pat. Nos. 5,526,454; 4,262,995; 4,466,696; 3,864,019; and 5,600,745. Notwithstanding these efforts, a better solution is needed.
The present invention provides a reliable, simple, and inexpensive method and apparatus for precise optical connection of an optical fiber and a waveguide. For example, in one embodiment of the present invention, an optical connector is provided. The optical connector includes a base with an optical fiber receiving section and a waveguide therein. The receiving section includes a flared channel having an opening at a peripheral side of the base. The channel has opposing orthogonal tapered sidewalls and a horizontal bottom perpendicular to the sidewalls. Inward from the opening, the channel narrows in a lateral direction, because the opposing sidewalls extend diagonally towards each other. The waveguide is optically accessible at a narrow inner end of the receiving section opposite the opening. The connector may also include a cover that attaches to the base.
The present invention also includes an optical fiber that can be used in a self-aligning manner with the optical connector described above. The optical fiber has a first end section that includes a tip of the fiber. Part of the cladding of the first end section is removed so as to form opposing orthogonal tapered sidewalls. The sidewalls extend diagonally towards each other in a direction towards the tip of the fiber. The angle of taper of the opposing orthogonal sidewalls of the optical fiber matches the angle of taper of the opposing orthogonal sidewalls of the receiving section of the connector. The first end section of the optical fiber also may have a horizontal bottom surface and an opposing horizontal top surface that are perpendicular to the orthogonal sidewalls.
An exemplary method of optically connecting the optical fiber and connector described above includes inserting the first end section of the optical fiber into the opening of the receiving section of the connector, and sliding the bottom surface of the first end section of the fiber laterally along the bottom surface of the receiving section of the base toward the waveguide at the inner end of the receiving section. The optical fiber is inserted until the orthogonal sidewalls of the first end section contact the correspondingly-angled orthogonal sidewalls of the receiving section. Meanwhile, the bottom surface of the first end section of the optical fiber rests on the bottom surface of the receiving section of the connector. By virtue of the reciprocal tapering of the abutting sidewalls of the first end section of the fiber and the receiving section, and the abutting bottom surfaces of the first end section of the fiber and the receiving section, the core at the tip of the first end section of the optical fiber is positioned immediately adjacent to the waveguide of the connector with precise three dimensional alignment. Optionally, an adhesive may be used to affix the abutting surfaces of the first end section and the receiving section. An optically clear adhesive may be between the tip and the waveguide, providing an optical path therebetween. Where the connector is provided with a cover, the cover can be closed over the fiber and the waveguide.